Halfturn

Inspiration

Athletes get coached on awareness all the time, but it's hard to practice alone. There's no one there to tell you when to scan or check your shoulder.

What it does

HalfTurn is a mobile app that helps athletes train scanning and awareness. It plays randomized audio cues while you train (like "check left" or "scan"). You can customize timing and cue types. In Turn & React mode, the phone camera uses on-device pose tracking to check that you actually turned after the cue. Sessions are saved locally so you can review history and stats.

How we built it

Built with Expo and React Native.

Text-to-speech for audio cues
MediaPipe Pose + VisionCamera for on-device body tracking
Custom scan detection on top of the pose data
SQLite for local session history The AI is on-device pose estimation. Nothing is uploaded to the cloud.

Challenges

Getting pose tracking reliable outdoors, keeping the audio drill simple enough for Expo Go, and making verification feel fair when the signal is noisy.